Methods and network nodes for performing a joint reception in a cellular radio communication network

ABSTRACT

The disclosure relates to cellular radio communication systems, and especially to performing a joint reception of uplink transmissions from user equipment devices UE 1 , UE 2 . A serving node and a cooperating node is described together with methods performed by each node. The serving node comprises a user equipment selector, a cooperating node selector and a radio element selector. The serving node also includes a user equipment allocator, a joint reception requester configured to order joint reception data from selected cooperating nodes, and a backhaul capacity obtainer configured to obtain a backhaul capacity of selected cooperating nodes. Especially, the radio element selector is adapted to select radio resource elements based on a determined backhaul capacity. By considering the backhaul capacity, the backhaul can be employed for joint reception without becoming overloaded. The cooperating node especially includes an element prioritizing unit configured to prioritize between data obtained from different the radio resource elements.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application is a 35 U.S.C. §371 National Phase Entry Applicationfrom PCT/EP2013/054260, filed Mar. 4, 2013, designating the UnitedStates, the disclosure of which is incorporated herein in its entiretyby reference.

TECHNICAL FIELD

The invention relates to cellular radio communication systems, andespecially to performing a joint reception of uplink transmissions fromuser equipment devices.

BACKGROUND

Joint reception, or coordinated multipoint reception (CoMP), of uplinktransmissions from user equipment units is a method for enhancing thereception quality of transmissions received from user equipment units.When performing a joint reception of uplink transmissions, a servingnode receives user data from a user equipment unit, both directly fromthe user equipment unit and from another network node, a so calledcooperating node, which cooperating node receives the uplinktransmissions and forwards user data to the serving node.

D1 (US2011/0080879) describes coordinated multipoint (CoMP) reception ofuplink signals in a cellular radio communication system (see §2). Uplinksignals are received at multiple antennas by a plurality of adjacentradio access points (§4). The received uplink transmissions aresubjected to a joint reception (§5). To reduce complexity during thejoint processing, the system of D1 does not use all possible antennasfor the reception. Instead only a subset of antennas are used (§6).Typically, the antennas where the strongest signal strengths can beexpected are selected. D1 suggests measuring the downlink signalsreceived by the user equipment in question (see claim 1 of D1).

Joint reception, as in D1 or otherwise, is beneficial in providing anenhanced reception of the uplink transmissions than single-nodereception. However, joint reception requires that a cooperating nodetransfer user data to the serving node. Such transfer in a transportnetwork is typically referred to as backhaul transmissions.

Since joint reception is beneficial compared to single-node reception aneed to use joint reception arises. However, using the backhaul forjoint reception may not always be possible since there is a risk ofcongestion in the backhaul links. If the backhaul is congested, thejoint reception may fail or be delayed. Such congestion may not beavoided even if the number of reception points is limited, as in D1.

SUMMARY

It is an aim of the invention to alleviate the drawbacks of the priorart when performing a joint reception in a cellular radio communicationsystem.

For this purpose the invention provides a method performed by a servingnode during a process of joint reception.

The method is performed in a cellular radio communication network, andincludes scheduling traffic for joint reception. The method is performedby a serving node and comprises: selecting at least one user equipmentunit, selecting at least one cooperating node, and selecting at leastone radio resource element. Each radio resource element consists of atleast one part of the radio resources available for uplinktransmissions, the available radio resource being defined by a timeperiod comprising at least one sub-frame defining a minimum time for onetransmission, and a frequency band comprising a plurality of sub-bandsprovided for scheduling in the cellular radio communication network.

The method of the serving node especially includes obtaining a backhaulcapacity of each cooperating node, and the selection of the at least oneradio resource element is based on at least one of the determinedbackhaul capacities. The method also includes ordering joint receptiondata from each selected cooperating node by transmitting at least oneordering message to each selected cooperating node, which at least oneordering message identifies each selected radio resource element, andincludes allocating the selected at least one user equipment unit foruplink transmission including transmitting at least one allocatingmessage to each allocated user equipment unit, which at least oneallocating message identifies each selected radio resource element.

The invention also provides a node for a cellular radio communicationnetwork that is configured for acting as a serving node when performinga joint reception, the node being adapted for scheduling traffic forjoint reception. The node comprises a user equipment selector configuredto select user equipment units for joint reception, a cooperating nodeselector configured to select cooperating nodes for the joint reception,and a radio element selector configured to select radio resourceelements for the joint reception, wherein each radio resource elementconsists of at least one part of the radio resources available foruplink transmissions, which available radio resource is defined by atime period comprising at least one sub-frame defining a minimum timefor one transmission, and a frequency band comprising a plurality ofsub-bands provided for scheduling in the cellular radio communicationnetwork.

By selecting the radio resource elements, which should be used for thejoint reception, on the bases of the capacity of the backhaul, the riskfor failure due to congestion of the backhaul is reduced.

The node further includes a joint reception requester configured toorder joint reception data from selected cooperating nodes bytransmitting ordering messages to the selected cooperating nodes, whichordering messages identifies the selected radio resource elements, andincludes a user equipment allocator configured to allocate selected userequipment units for uplink transmission including configured to transmitallocating messages to allocated user equipment units, which allocatingmessages identifies the selected radio resource elements. The node ischaracterised in comprising a backhaul capacity obtainer configured toobtain a backhaul capacity of selected cooperating nodes, and in thatthe radio element selector is adapted to select radio resource elementsbased on a determined backhaul capacity.

The invention also provides a method of a cooperating node in a cellularradio communication network, which includes participating in jointreception, wherein an uplink transmission of a user equipment isreceived by a plurality of reception nodes, one of the reception nodesbeing a serving node, at least one of the reception nodes being acooperating node, each cooperating node being provided to obtain datafor joint reception from the received uplink transmission and forwardthe obtained data to the serving node.

The method is performed by a cooperating node and comprises: receivingan order for joint reception of at least two radio resource elementsfrom the serving node, receiving the at least two radio resourceelements, obtaining data from each received radio resource element, andforwarding the obtained data to the serving node. The method ischaracterized by prioritizing at least one radio resource element of theat least two radio resource elements before forwarding the obtaineddata, so that the data obtained from the prioritized radio resourceelement is forwarded before the data obtained from the other radioresource element.

The invention also provides a node configured to act as a cooperatingnode when performing a joint reception in a cellular radio communicationnetwork. The node is adapted to obtain data for joint reception fromuplink transmission and forward the obtained data to a serving node. Thenode comprises an order obtainer configured to receive orders for jointreception of radio resource elements from the serving node, an uplinktransmissions obtainer configured to receive the radio resource elementsfrom user equipment units, a data obtainer configured to obtain datafrom received radio resource elements, and a data messenger configuredto forward the obtained data to the serving node. The cooperating nodeis characterized in that it comprises an element prioritizing unitconfigured to prioritize the radio resource elements, so that the dataobtained from the prioritized radio resource element is forwarded by thedata messenger before the data obtained from the other radio resourceelement.

In a preferred embodiment, the cooperating node includes an elementprioritizing unit configured to prioritize between data obtained fromdifferent the radio resource elements, which prioritization is based onthe type of the radio resource elements (B1, B2) and/or an identity ofthe user equipment unit (UE1) in question, and/or an indication in thejoint reception order that indicates priority to a specific resourceelement (B1, B2).

Generally, all terms used in the claims are to be interpreted accordingto their ordinary meaning in the technical field, unless explicitlydefined otherwise herein. All references to “a/an/the element,apparatus, component, means, step, etc.” are to be interpreted openly asreferring to at least one instance of the element, apparatus, component,means, step, etc., unless explicitly stated otherwise. The steps of anymethod disclosed herein do not have to be performed in the exact orderdisclosed, unless explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is now described, by way of example, with reference to theaccompanying drawings, in which:

FIG. 1 illustrate parts of a cellular radio communication system, inwhich communication system the invention can be performed;

FIG. 2 is a simplified flow chart illustrating embodiments of methodsteps performed by the serving node;

FIG. 3 is a simplified flow chart illustrating embodiments of methodsteps performed by a cooperating node;

FIG. 4 is a simplified flow chart illustrating embodiments of methodsteps performed by a user equipment unit;

FIGS. 5a to 5b illustrate embodiments of radio resource elements intime/frequency diagrams;

FIG. 6 illustrate parts of a serving node according to an embodiment;

FIG. 7-9 illustrate parts of the serving node of FIG. 6 in more detail;

FIG. 10 illustrate parts of a cooperating node according to anembodiment

FIG. 11 is a signalling diagram illustrating exchange of signals in anembodiment of performing a joint reception.

DETAILED DESCRIPTION

The invention will now be described more fully hereinafter withreference to the accompanying drawings, in which certain embodiments ofthe invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided byway of example so that this disclosure will be thorough and complete,and will fully convey the scope of the invention to those skilled in theart. Like numbers refer to like elements throughout the description.

A suitable cellular radio communication system for implementing theinvention is a 3GPP system (3rd Generation Partnership Project), andembodiments are described in relation to the LTE standard (Long-TermEvolution). However, the invention may in similar ways be implemented inother cellular radio communication systems, such as for example GSM,TD-CDMA, and UMTS.

FIG. 1 illustrates a cellular radio communication system 1 comprising anumber of network nodes (2, 3, and 4) for communicating with userequipment units UE1, UE2. During communication, one of the network nodeswill serve as a serving node 2 for the user equipment units UE1, UE2,and the other network nodes (3, 4) may be used as reception nodes 3, 4for uplink transmissions from the user equipment units UE1, UE2 andpotentially be used as cooperating nodes 3 for performing a jointreception, or coordinated multipoint reception, of uplink transmissionsfrom at least one of the user equipment units UE1, UE2. The networknodes 2, 3, 4 are interconnected by a backhaul BH comprising backhaullinks 5, 6, 10. In FIG. 1, one of the reception nodes 3, 4 has beenselected for joint reception and is illustrated as a cooperating node 3.The operations performed by other cooperating nodes 3 are similar andfor illustrative purposes only one cooperating node 3 is included in thefigure, and only one other reception node 4. The backhaul connectionbetween the network nodes 2, 3, 4 are for illustrative purpose indicatedby single links 5, 6 referred to as backhaul links 5, 6. However, in areal system the actual topology of the backhaul BH varies and includesseveral links and may also pass other network nodes than thoseillustrated. Thus, the backhaul links 5, 6 are a part of the transportnetwork of the cellular radio communication system 1, usually comprisingoptical fibres, microwave communication links, electrical communicationlinks, non-line of sight wireless links or a combination of such links.The serving node 2 is also illustrated as having a link 10 to thebackhaul, in addition to the links 5, 6 to the reception nodes 3, 4,which link 10 is used for communication with other nodes (notillustrated) of the cellular radio communication system 1. The physicallinks 5, 6, 10 may be the same but for illustrative purposes theinterconnection links 5, 6 are illustrated separately, by a dotted line,as extending between the serving node 2 and the other reception nodes 3,4.

The serving node includes an analysing unit 7, a scheduling unit 8, anda joint reception unit 9. The joint reception unit 9 is provided forperforming a joint reception of UL transmissions from the user equipmentunits UE1, UE2. For performing a joint reception, the joint receptionunit 9 is configured to combine UL transmissions received directly fromthe user equipment units UE1, UE2 with data forwarded from thecooperating node 3. The cooperating node 3 includes a joint receptioncooperating unit 40 configured for receiving UL transmissions from theuser equipment units UE1, UE2, obtain data from the UL transmissions andforward the obtained data to the serving node 2 via the backhaul link 5.

The serving node 2 is configured to select a cooperating node 3 from theavailable reception nodes 3, 4 and to select user equipment units UE1for performing the joint reception. The selection is based on the radiolink quality between the user equipment units UE1, UE2 and the receptionnodes 3, 4. For this purpose the serving node 2 includes an analysingunit 7 that is configured to determine the quality of the radio links,and a scheduling unit 8 provided to select a user equipment unit UE1 andone or more cooperating nodes 3 for performing the joint reception ofthe UL transmissions from the user equipment unit UE1.

Each potential cooperating node 3, 4 includes an analysing unit 30configured to determine the radio link quality to the user equipmentunits UE1, UE2, which radio link quality may be transferred to theserving node 2 for assisting in establishing the radio link quality ofthe UL from the user equipment units UE1, UE2 to the potentialcooperating node 3.

Also, the user equipment units UE1, UE2 include means for determining aradio link quality to the potential cooperating nodes 3, and the servingnode 2 may request and receive such indications of radio link qualityfrom the user equipment units UE1, UE2.

The serving node 2 is adapted for allocating radio resources for thejoint reception on the bases of a backhaul capacity that comprises thetransmission capacity of the backhaul, illustrated as a backhaul link 5,between the cooperating node 3 and the serving node 2. The backhaulcapacity also comprises the capacity of the cooperating node 3 toparticipate in a joint reception process, such as including anindication of the current communication load experienced by thecooperating node 3, or the currently available computing capacity of thecooperating node 3.

FIG. 11 illustrates a signalling diagram between a serving node (2 inFIG. 1), a cooperating node (3 in FIG. 1), and a user equipment unitUE1, which cooperating node 3 and user equipment unit UE1 are potentialunits for performing a joint reception and subsequently are selected forthe process of joint reception. The serving node 2 transmits 100 a radioquality request to the “potential” user equipment unit UE1, and a radioquality request to the “potential” cooperating node 3. The potentialuser equipment unit UE1 replies 302 by transmitting a radio qualitymessage indicating the radio link quality to the potential cooperatingnode 3. The potential cooperating node 3 replies to the serving node bytransmitting 202 a radio quality message, which radio quality messageindicates the radio link quality to the potential user equipment unitUE1. Based on the radio quality messages, the serving node 2 may selectthe user equipment unit UE1 and the cooperating node 3 for jointreception. The serving node 2 may also transmit 104 a capacity requestto the potential cooperating node 3 for determining the backhaulcapacity for a joint reception. In such a case, the cooperating node 3replies 204 by transmitting an indication of its capacity in a capacitymessage to the serving node 2, which indication may include the capacityof the cooperating node 3 for participating in a joint reception, suchas including its computing capacity. Based on the radio link qualitymessages and the capacity message the serving node 2 selects thecooperating node 3 and the user equipment unit UE1 for the process ofjoint reception and selects a radio resource element that should be usedby the user equipment unit UE1 and be received by the cooperating node3. The serving node 2 transmits 108 a joint reception order to thecooperating node 3 that identifies the radio resource element of theuplink transmissions from the user equipment UE1, i.e. the uplinktransmissions that should be jointly received. The serving node 2transmits an allocating message to the user equipment unit UE1identifying the radio resource element for the uplink transmission, theallocating message to the user equipment unit UE1 may identify both theradio resource element that should be jointly received as well as radioresources that are only received by the serving node 2 in a single-nodereception. The user equipment unit UE1 transmits 304 using the allocatedradio resource element, and the uplink transmissions that should bejointly received are received by both the cooperating node 3 and theserving node 2. The cooperating node 3 obtains data from the uplinktransmissions and forwards the obtained data to the serving node 2, sothat the serving node 2 can perform a joint reception of the directlyreceived uplink transmissions and the uplink transmissions received viathe cooperating node 3.

The serving node 2 may also schedule the user for single-node receptiononly in which case the serving node 2 sends 114 an allocating message tothe user equipment unit UE1, without sending a corresponding jointreception order to any other reception node 3, 4.

FIG. 2 illustrates method steps being performed by a serving node 2 whenselecting cooperating nodes 3 and user equipment units UE1 forperforming a joint reception and method steps performed during a processof joint reception. The method starts with obtaining 100 an indicationof communication quality of a radio link or interface, between a userequipment unit UE1, UE2 and at least one other node 3, 4. The obtainedindication of radio link quality is used for determining the possibilityof performing a joint reception, and for selecting suitable combinationsof user equipment units UE1, UE2 and cooperating nodes 3, 4.

The invention can suitable be implemented in a network node alreadybeing adapted for exchanging operating data, such as radio communicationquality indications, between neighboring nodes. Such indications ofradio link quality may therefore already have been received and storedby the serving node 2. In such a case the serving node 2 is suitablyconfigured to obtain an indication of radio communication qualitybetween user equipment units UE1, UE2 and potential cooperating nodes 3,4 by retrieving the radio communication quality indication from its ownmemory. If the serving node 2 is not adapted for exchanging operatingdata with neighboring nodes it should be adapted to obtain such data,for example by including, in the step of obtaining 100, sending arequest for a radio quality indication to the user equipment unit UE1,UE2 and/or the cooperating node 3, 4.

On the basis of the radio communication quality, the serving node 2 isadapted to group user equipment units UE1, UE2 into one of two sets S1and S2. Set S1 consists of user equipment units UE1 having a radiocommunication quality with a potential cooperating node 3, 4 better thana criterion. Set S2 consists of user equipment units UE2 having a radiocommunication quality with a potential cooperating node that is worsethan the criterion. In this way the serving node 2 may store sets ofuser equipment units suitable for being selected for joint reception bymeans of a corresponding cooperating node 3.

The criterion for grouping the user equipment units into the sets S1 andS2 is in an embodiment based on for example the path loss from the userequipment unit UE1, UE2 to the cooperating node 3, 4. The criterion isin an embodiment based on the difference in path loss between the userequipment unit UE1, UE2 and the serving node 2, and between the userequipment unit UE1, UE2 and the cooperating node 3, 4. The userequipment units UE1, UE2 having the least difference, i.e. below athreshold, are grouped into set S1.S ₁={UE_(i):PL_(S)(UE_(i))−PL_(C)(UE_(i))<Δ}  (Equation 1)where PL_(S)( ) is the pathloss, in dB, on the UL or DL between theserving node (2 in FIG. 1) and user equipment number i (UE_(i)) (UE₁,UE₂ in FIG. 1), and PL_(C)( ) is the pathloss between the (potential)cooperating node (3, 4 in FIG. 1) and user equipment unit i (UE1, UE2 inFIG. 1). Δ is a threshold level, which is set at least so high that ameaningful reception can be expected at the cooperating node.

In an alternative embodiment the criterion for grouping the userequipment units can be based on calculating a gain in communicationquality, e.g. in dB, that the user equipment units UE1, UE2 will get ifa joint reception is performed in relation to if a single-node receptionis performed. Such a calculation can be made on the basis on a radiolink quality report containing, in the example of LTE, a SINR(Signal-to-Noise-and Interference Ratio). For example, in LTE, a postMMSE SINR (Minimum Mean Square Error) per sub-carrier indication can beused, and if the invention is implemented in other cellular radiocommunication systems a similar estimation of gain can be made using theradio quality reports of the system in question. Thus, the serving node2 is suitably configured, as described above, to obtain a radio linkquality indication, or measure, to prioritize user equipment units UE1,UE2 that is likely to gain most in communication quality utilizing thelimited cooperating capacity of the backhaul and the cooperating nodes3. The estimation of a gain of a joint reception may be approximatedwith an estimated gain in radio link quality.

One such criterion is thusG _(i)={UE_(i):SINR_(C)(UE_(i))−SINR_(S)(UE_(i))>ΔSINR}  (Equation 2)where ΔSINR is a threshold, and wherein the user equipment units UE_(i)(of the user equipment units UE1-UE2) with the highest estimated gainG_(i) based on SINR (in dB) of a cooperating node (SINR_(C)) in relationto the SINR of the serving node (SINR_(S)) is selected to the set ofuser equipment units S1 being suitable for performing a joint receptionwith the cooperating node 3, 4 in question.

The method continues with selecting 101 a user equipment unit UE1 forjoint reception, which selecting is based on the obtained radiocommunication quality, preferably selected from the set S1 of userequipment units UE1 that are suitable for joint reception by means of acorresponding cooperating node 3.

The selecting 101 may include selecting a plurality of user equipmentunits UE1 for joint reception, wherein all of the selected userequipment units UE1 belong to S1.

The method continues with selecting 102 at least one cooperating node 3,which cooperating node is, or nodes are, the cooperating node or nodes 3that correspond to the selected user equipment unit UE1 of set S1.

The selecting 102 of the cooperating nodes 3 is based on the obtained100 indication of radio communication quality, especially cooperatingnodes 3 corresponding to the selected user equipment units UE1 of S1.

The method further includes determining 103 a time period T based on amaximum allowed latency for performing joint detection. This time periodT indicates a time period during which the data for joint reception canbe received still complying with requirements for delays when receivingdata in the cellular radio communication network 1. The time period Tcan be used for determining a time window during which radio resourcesof the radio communication interfaces between the user equipment unitsUE1 and the cooperating node 3 can be used for performing one jointreception.

The relationship between radio resources in the cellular radiocommunication system 1 and the time period T is illustrated in moredetail in FIGS. 5a and 5b . The radio resources consist of a frequencyband which is used for transmissions during time periods comprising aminimum sub frame, or duration, referred to as TTI (transmission timeinterval) in LTE. The frequency band is divided in the cellular radiocommunication system 1 into a plurality of sub-bands.

FIGS. 5a and 5b illustrates the total radio resource A allocated to auser equipment unit UE1 during the time period T, wherein a part B1 andB2, respectively, of the total radio resource A have been selected forjoint reception. FIG. 5a illustrates a situation where the totalfrequency band in one TTI (B1) of the time period T has been selected.FIG. 5b illustrates a situation where a number of sub-bands of the totalscheduled frequency band have been selected in every TTI (B2) of thetime period T.

FIG. 5a illustrates an example of a situation wherein the firstsub-frame B1 allocated to one user equipment unit UE1 is allocated forjoint reception. In this example, the backhaul capacity is limited toobtain data from B1 and transmit the obtained data during the whole timeperiod T. The data obtained from the sub-frame B1 is stored in thememory of the cooperating node 3, so that it is buffered, until it canbe transmitted in the backhaul link. This will induce a latency.

FIG. 5b illustrates an example of a situation wherein a part B2 of everysub-frame A2 that is scheduled to one user equipment unit UE1 isallocated for joint reception. In this example, the bandwidth of thedata obtained from each sub-band B2 a-n is small enough to betransmitted in the backhaul as soon as it is obtained, and in thissituation no latency will be induced due to limitation in bandwidth ofthe backhaul. The remaining sub-bands C2 a-n of the sub-frames A2 a-n isalso allocated to the user equipment unit UE1 but is received as singlenode receptions by the serving node 2.

It is easier to implement scheduling wherein the user equipment unit UE1uses the same allocation over its total transmission, during onesub-frame, in the frequency band (A, B1, A2 a-n). Since joint receptionprovides an enhanced reception of the transmissions, a link adaptationthat allows a higher data rate can be used in the sub-frame element B1than in the sub-band elements B2 a-n where the sub-band elements C2 a-nthat are the subject of single-node reception are transmitted by theuser equipment unit UE1 with the same link adaptation as the sub-bandelements B2 subjected to the joint reception. In the example of FIG. 5a, the remaining sub-frames A, that are the subject of single-nodereception by the serving node, use a link adaptation, of lower datarate, to provide a satisfying reception quality. Therefore, it may beadvantageous to use sub-frame elements B1 even if latency is introduced.

The user equipment unit UE1 will, in the example of FIG. 5a , transmitduring the whole period T, using a first link adaptation for the firstsub-frame B1 of the frequency band, and a second link adaptation for thetransmissions in the remaining sub-frames of A.

The user equipment unit UE1 will, in the example of FIG. 5b , transmitduring the whole period T using the same link adaptation.

Thus, a first link adaptation scheme is used by the serving node 2 forscheduling the sub-frame B1 subjected to the joint reception, a secondlink adaptation scheme is used for scheduling the sub-frames A subjectedto the single-node reception, and a third link adaptation scheme is usedfor scheduling the combined sub-frames A2 a-n that are the subject bothfor a joint reception, i.e. the sub-band elements B2 a-n, and for thesingle-node reception, i.e. the sub-band elements C2 a-n.

The method further includes obtaining 104 a backhaul capacity of the, oreach, selected cooperating node 3. The backhaul capacity can beretrieved from a memory of the serving node 2 in cases where theinvention is implemented in a network node, such as a base station,already configured to exchange such data with neighboring nodes (such as3, 4 in FIG. 1). Thus, obtaining can be performed for example by readingfrom the memory, obtain it from an operator or management interface, ora Self-Optimizing Network (SON) interface. Alternatively, obtaining 104backhaul capacity includes requesting an indication of the backhaulcapacity from the cooperating node 3. Also, in case the invention isimplemented in a network node 2 already configured to obtain or exchangeat least a part of the backhaul capacity data, such part of the backhaulcapacity data can be retrieved from its memory in combination withrequesting the remaining backhaul capacity data from the cooperatingnode 3. The backhaul capacity comprises, in a preferred embodiment: anindication of latency for communication from the cooperating node 3 tothe serving node 2; and an indication of available bandwidth for sendingthe joint reception data on the link 5 of the backhaul from thecooperating node 3 to the serving node 2; an indication of the currentload of the cooperating node 3; and an indication of computing capacityof the cooperating node 3.

The method continues with selecting 105 at least one radio resourceelement B1, B2 based on at least one of the determined backhaulcapacities. The serving node 2 is configured to make the selection ofthe radio resource element B1, B2 that consists of at least one part ofthe radio resources A available for uplink transmissions. Returning toFIGS. 5a and 5b , the available radio resource A is defined by the timeperiod T comprising at least one sub-frame (TTI) defining a minimum timefor one transmission, and a frequency band comprising a plurality ofsub-bands provided for scheduling in the cellular radio communicationnetwork 1. FIGS. 5a and 5b illustrates parts of the total radio resourceA that can be selected for joint reception transmissions.

FIG. 5a illustrates an example where the backhaul capacity during timeperiod T equals, or is larger, than the total backhaul capacity requiredto carry the data for joint reception of one TTI, but less than requiredfor continuous reception during time period T. The serving node 2 istherefore adapted to allocate B1 for joint reception during the firstTTI, but use the remaining part of the radio resource A eithersingle-node reception only of the same UE1, or for other traffic, so asnot to cause a congestion of the backhaul. However, allocating radioresource element B1 is not the only possibility to avoid congestion ofthe backhaul.

FIG. 5b illustrates a situation where the backhaul capacity during timeperiod T equals, or is larger, than the total amount of radio resourceelements B2 a, B2 b, . . . , B2 n. Also, each radio resource element B2a, B2 b, . . . , B2 n is smaller than or equal to the backhaultransmission capacity during each sub frame TTI. The serving node 2 istherefore adapted to allocate the radio resource elements B2 a, B2 b, .. . , B2 n during the time period T, wherein each radio resource elementB2 a, B2 b, . . . , B2 n is of type B2. Thus, the serving node 2 istherefore adapted to allocate B2 or B2 a, B2 b, . . . , B2 n during theTTIs of time period T, but use the remaining part of the radio resourceA2 for other traffic of the user equipment in question, i.e. traffic(using C2 a-n) for single node reception, so as not to cause acongestion of the backhaul. If the available backhaul capacity is lessthan B1, the serving node may be configured to allocate a radio resourceelement B2 only during the first TTI, so as not to congest the backhaul.

Therefore, the serving node 2 is configured to use radio resourceelement B1, B2 being of a type selected from a group of resourceelements comprising: a sub-frame element B1 consisting of at leastone-sub frame of the whole frequency band; and sub-frequency element B2,B2 a, B2 b, . . . , B2 n consisting of one sub-band in some or allsub-frames of the time period T.

As indicated above, the backhaul capacity comprises an indication oflatency, and an indication of available bandwidth for sending the jointreception data on the backhaul, using a backhaul link 5 of the backhaul,and an indication of computing capacity of the cooperating node 3. If,for example, the available bandwidth of the backhaul link provides abottle-neck for the joint reception, but the computing capacity of thecooperating node 3 is larger than required, the computing capacity canbe used for reducing the bandwidth requirement of the joint reception.Therefore, the serving node 2 is adapted to consider instructing thecooperating node 3 to refine the data received in the uplinktransmissions to a certain level so that the bandwidth requirements forthe transmissions on the backhaul link 5 is decreased. The methodtherefore includes a step of determining a level of refinement 107 ofthe UL transmissions that should be received by the cooperating node 3and includes an indication of a level of refinement when ordering ajoint reception 108 from the cooperating node.

The method comprises selecting 106 a link adaptation. In an embodimentthe link adaptation is selected from different sets of link adaptationsfor joint reception processes, such as using radio resource element B1of FIG. 5, and single node reception, such as when using radio resourceelement A. Also, when an uplink transmission from a user equipment unitUE1 are the subject of both joint reception and single node reception,such as using radio resource elements B2 a and C2 a of FIG. 5b , a thirdlink adaptation is selected, which third link adaptation is differentfrom both the first link adaptation used for joint reception as well asthe second link adaptation used for single node reception.

The method further comprises determining 107 a level of refinement onthe basis of the backhaul capacity, especially a further refinement whenthe backhaul transmission capacity is low and the computing capacity ofthe cooperating node 3 is higher than needed for not performing such arefinement. The levels of refinement used are, in an embodiment,selected from a group of refinement levels including at least two of:time domain data; frequency domain (FFT) data symbols for the entiresystem bandwidth; user extracted frequency domain data symbols;equalized I/Q symbols; soft-bits and hard-bits.

The method further includes transmitting 108 an ordering message to eachselected cooperating node. The message comprises an order, or request,of joint reception data from each selected cooperating node 3 by. Theordering message includes an identification of the, or each, selectedradio resource element or elements B1, B2, B2 a-B2 n.

In an embodiment, the order message 108 comprises an indication of alevel of refinement of the radio resource element or elements B1, B2, B2a-B2 n.

The invention may suitably be implemented in cellular radiocommunication systems 1 wherein each user equipment unit UE1, UE2 isattended a certain quality of service level (Q o S). In such a case, theorder message includes, in an embodiment, an instruction to prioritizebetween a plurality of radio resource elements B1, B2, wherein theprioritization corresponds to the Q o S level of the user equipment unitUE1 for which the radio resource elements B1, B2 are allocated.

The method continues with allocating 109 the selected at least one userequipment unit UE1 for uplink transmission, and with sending anallocating message 110 to the user equipment unit UE1.

In case a plurality of user equipment units UE1 have been selected forjoint reception, the allocating 109 includes allocating each of theselected user equipment units UE1 to the respective radio resourceelement B1, B2.

If the selected user equipment units UE1 is attended a certain qualityof service level (Q o S) in the cellular radio communication network,the allocating 109, may in an embodiment, include selecting a certaintype of radio resource element, B1 or B2, based on the quality ofservice level of each selected user equipment unit UE1.

The transmitting 110 of at least one allocating message to eachallocated user equipment unit UE1, comprises an allocating message thatidentifies each selected radio resource element B1, B2, and indicatesthe link adaptation. In case the uplink transmissions from the userequipment unit UE1 should both be received by the serving node 2 as asingle-node reception, the allocating message identifies both the radioresource element B2 that should be jointly received as well as the radioresource element C2 that should only be received by the serving node 2,for example the allocating message identifies a radio resource elementA2 that includes both the radio resource element B2 that is jointlyreceived as well as the radio resource element C2 that is the subject ofthe single-node reception.

The joint reception process has then been initiated and the methodcontinues with receiving in the uplink transmission on the radioresource elements B1, B2 in the serving node 2 directly. Data is at thesame time obtained by each cooperating node 3.

The method continues with receiving 112 the obtained data from eachcooperating node 3. Thus, the data that each cooperating node hasobtained from the selected radio resource element B1, B2, B2 a-n andforwarded by means of each respective backhaul link 5 is received in theserving node 2.

The serving node 2 then perform 113 a joint reception of the directlyreceived uplink transmission (B1, B2) and the data from each cooperatingnode 3, which data has been obtained from the uplink transmissions (B1,B2). The directly received data is, during an embodiment of the jointreception, refined by the serving node 2 to the same level as refined bythe cooperating node 3.

The method also includes allocating 114 user equipment units UE1, UE2for single-node reception by means of the serving node 2 allocating onone part of the radio resources A other than the radio resource elementsB1, B2 that have been selected for joint reception.

The allocating 114, of at least one user equipment unit UE1, UE2 forsingle-node reception only during another sub frame TTI than thesub-frame TTI selected for joint reception, may be used also for userequipment units UE1 that has also been allocated for radio resourceelement B1, B2 selected for joint reception. Thus, when allocating 114user equipment units UE1, UE2 for single-node reception only, theserving node 2 is adapted to select user equipment units UE1, UE2 fromS1 and S2. Alternatively, user equipment units UE2 are selected onlyfrom S2 when allocating 114 user equipment units for single-nodereception.

FIG. 3 describes a method performed by a cooperating node 3 whenparticipating in a joint reception process. In such a process, theuplink transmission of a user equipment unit UE1 is received by aserving node 2 and one or more cooperating nodes 3. Each cooperatingnode 3 could suitably be configured in accordance with these methodsteps. In the process, each cooperating node 3 is configured to obtaindata for joint reception from the uplink transmissions, i.e. from radioresource elements B1, B2, and forward the obtained data to the servingnode 2 so that the serving node 2 can perform the joint reception.

The method performed by a cooperating node 3 comprises determining 201an indication of the radio communication quality with a user equipmentunit UE1, UE2 and transmitting 202 an indication of the radiocommunication quality to the serving node 2. In this way, thecooperating node 3 determines a radio communication quality on the basisof uplink transmissions from the user equipment unit UE1, UE2.

It should be noted that these steps 201, 202, of determining andtransmitting an indication of radio communication quality, are notnecessary for performing a joint reception. As indicated with referenceto FIG. 2, the radio communication quality may instead, for example, bebased on measurements of the downlink performed by the user equipmentunits UE1, UE2, such as measuring reception levels of broadcasts ofneighboring base stations 3, 4 that may be selected as cooperating nodes3.

The method continues with determining 203 a capacity of the cooperatingnode for participating in the joint reception. The cooperating node 3 isin an embodiment configured to establish its current load, or itscurrently available computing capacity. The determining 203 of capacityincludes preferably the capacity of the cooperating node 3 for receivingtransmissions, obtaining data and forwarding the obtained data to theserving node 2. In this way, the serving node 2 can utilize the capacityreceived from the cooperating node 3 to obtain a backhaul capacity,which may also include capacity that the serving node 2 obtains fromalready stored data about the transmission bandwidth of the backhaullink and the computing capacity of the cooperating node 3.

The method includes transmitting 204 an indication of the capacity ofthe cooperating node 3 to the serving node 2. Especially, such anindication comprises an indication of latency, and/or an indication ofavailable bandwidth for sending the obtained data on to the serving node2 and/or an indication of computing capacity of the cooperating node 3.There are different ways of determining the backhaul capacity that iscurrently available for joint reception and the serving node 2 andcooperating node 3 can therefore be configured to share the processesfor determining the backhaul capacity in different ways, eachparticipating by establishing a certain part of the backhaul capacity.For example, the indication of latency may be derived from the availablebandwidth of the backhaul 5, but latency and bandwidth may beindependently indicated and the serving node 2 may be employed forproviding the backhaul capacity without the need for the cooperatingnode 3 to making any such calculations or measurements. Alternatively,or in addition, other ways of obtaining an indication of the capacityfor backhaul transmissions may be employed using other network functionsdepending on the cellular radio access system wherein the invention isimplemented, for example probes in the transport network may be employedthat measure the capacity of the transport network. Also, the servingnode 2 may employ such probes to obtain an indication of transmissioncapacity without the need for requesting such an indication from thecooperating nodes 3.

The backhaul capacity indication sent from the cooperating node 3includes in an embodiment an indication of the currently availablecomputing capacity of the cooperating node 3. In an embodiment, thebackhaul capacity indication may instead or in addition include anindication of the current traffic load of the cooperating node 3, whichcan be used by the serving node 2 to determine if the cooperating node 3has additional computing capacity that may be used in the jointreception for refining the data the cooperating node 3 obtains from theuplink transmissions in the radio resource elements B1, B2.

The serving node 2 may have been able to determine the backhaul capacityfrom other sources than from the cooperating node 3, and the methodperformed by the cooperating node 3 may in such a case start withreceiving an order for joint reception 205.

The receiving 205 of an order for joint reception includes anidentification of at least one radio resource element B1, B2 that thecooperating node 3 should receive and obtain data from. The order mayidentify a plurality of radio resource elements B1, B2 from the servingnode 2. The order may for example indicate a sub-band B2 a that shouldbe received during a number of TTI sub-frames, such as consecutive TTIs.The sub-band B2 may be a sub-band of the total uplink transmissions B2,C2 of the user equipment unit UE1 in case only a part of the uplinktransmissions of the user equipment unit UE1 is the subject of the jointreception.

The received 205 order may suitably comprise an indication of linkadaptation.

The received 205 order may also comprise an indication of a level ofrefinement of each resource element B1, B2, and in such a case the dataof the uplink is subsequently obtained 207 to the indicated level ofrefinement.

The method further includes receiving 206 the radio resource element orradio resource elements B1, B2, and obtaining 207 data from each of thereceived radio resource elements B1, B2.

When more than one radio resource element is received for jointreception the method may further include making a prioritization 208 ofat least one B2 of the at least two radio resource elements B1, B2.

In the subsequent step, the cooperating node forwards 209 the obtaineddata. The prioritizing is based on a priority indication in the received205 order message. In this way the data obtained from the prioritizedradio resource element B1, B2 is forwarded in the backhaul link at ahigher priority than the data obtained from the other radio resourceelement B1, B2.

The prioritization can be implemented in the cooperating node 3 as arule, i.e. the cooperating node 3 may be programmed to apply theprioritization in accordance with a prioritization rule, wherein aspecific type of radio resource element B1, B2 is prioritized.Alternatively, or additionally, the serving node 2 may be adapted tosend a prioritization instruction including an indication on which typeof radio resource element B1, B2 that should be prioritized.

For the cooperating node the joint reception process continues withforwarding 209 the obtained data to the serving node 2 until all theuplink transmissions of the joint reception process have been received,refined and forwarded.

FIG. 4 illustrates method steps performed by a user equipment unit UE1during selection of user equipment units UE1, UE2 for joint receptionand being subjected to joint reception. These steps may be performed byexisting user equipment units UE1, UE2, of for example an LTE system,and for performing the invention there is no need to carry out anymodifications of existing user equipment units.

The method includes receiving a request for radio communication quality300 with one or more potential cooperating nodes 3, 4. The userequipment unit UE1, UE2 determines 301 the radio communication qualitywith each cooperating node 3 indicated in the request. For example theuser equipment unit UE1, UE2 may measure power levels of broadcasts itreceives from neighboring nodes of the cellular radio communicationsystem 1. The user equipment unit UE1, UE2 continues with transmitting302 the determined radio communication quality. The determining 301 andtransmitting 302 may be the same measures taken for the purpose ofproviding candidate network nodes for a handover in the cellular radiocommunication system 1, and may therefore be the same steps as in thehandover process.

The user equipment unit UE1 receives 303 an allocating message. Theallocating message identifies one, or more radio resource element B1, B2and C2, together with an indication of a link adaptation to be used forthe transmission. The method performed by the user equipment unit UE1continues with transmitting user data and receiving 305 furtherallocating messages. The user equipment unit UE1 need not be consciousabout which transmissions, such as using radio resource elements B1 orB2, are the subject of joint reception and which are the subject ofsingle-node receptions, such as C2.

FIG. 5a illustrates a sub-frame element B1 consisting of at leastone-sub frame and comprises the whole frequency band that is allocatedto a user equipment unit UE1 during each sub-frame. Radio resource Aindicates the radio resource elements available during the total timeperiod T, wherein the first sub-frame, radio resource element B1, hasbeen selected for a joint reception. The remaining parts, sub-frames andsub-bands, may be used for other traffic, such as single-node receptionof the transmissions from the selected user equipment unit UE1. Theremaining part of the radio resources A during the time period T may beused for traffic from other user equipment units. However notillustrated in FIG. 5a , the radio resource A during time period T mayinclude a plurality of sub-frames B1 used for joint reception. Each ofthese sub-frames should be selected on the basis of the capacity of thebackhaul so as not to overload the backhaul.

FIG. 5b illustrates sub-frequency elements B2 a-n consisting of onesub-band in every sub-frame of the time period. FIG. 5b also illustratessub-frequency elements C2 a-n consisting of sub-bands in every sub-frameof the time period. Together the two types of sub-band elements B2 a-nand C2 a-n, respectively, make up sub-frame elements A2 a-n, thatconstitute sub-frames allocated to a specific user equipment unit UE1.Thus, the sub-frames A2 a-n are mixed sub-frames, each comprising asub-band element B2 a-n for joint reception and a sub-band element C2a-n for single-node reception.

FIGS. 6-9 illustrate a serving node 2 provided with a controller 12according to an embodiment of the invention. The figure illustratesfeatures needing consideration when implementing the invention in a basestation and for clarity purposes a detailed description of otherfunctions that a base station normally performs in a cellular radiocommunication system have been omitted. The FIGS. 6-9 illustrate anetwork node 2 adapted for performing the method of the serving node 2as described in FIG. 2. For this purpose, the serving node 2 is providedwith a controller 12 comprising a processor and memory which has beenmodified so that the serving node 2 has been configured for performingthe method of the embodiments of the invention. The functions (7-9,71-74, 80-89, 91-93, 861-863) indicated may suitably be implemented assoftware function that when executed by the processor of the controller12 employing the memory controls the serving node 2 to perform themethods of the embodiments of the invention. Thus the analyzing unit 7,the scheduling unit 8 and joint reception unit 9 are illustrated asparts of the memory storing computer program code, which when executedby the controller 12 makes the serving node 2 perform the functions.

FIG. 6 shows a serving node 2 comprising a radio communication interface11 for communicating with user equipment units UE1, UE2. In the contextof the invention the radio communication interface 11 is provided forreceiving uplink transmission on radio resource element B1, B2 selectedfor a joint reception process. The radio communication interface is alsoprovided for downlink transmissions to user equipment units UE1, UE2 andfor receiving uplink transmissions from user equipment units UE1, UE2for single-node reception, such as on radio resource elements C2 (ofFIG. 5b ) or A (of FIG. 5a ).

The serving node 2 also comprises a backhaul communication interface 13,which in the context of the invention, especially is provided forreceiving data obtained by a cooperating node 3 for the purposes ofperforming a joint reception. The controller 12 comprises a jointreception unit 9 configured to perform a joint reception of the uplinktransmission B1, B2 received directly from the user equipment units UE1,and the data from each cooperating node 3. The joint reception unit 9will be described in more detail with reference to FIG. 9.

The controller 12 also comprises an analyzing unit 7 and a schedulingunit 8. The analyzing unit 7 is configured for determining radiocommunication quality between user equipment units UE1, UE2 and otherreception nodes 3, 4 and also the backhaul capacity for the purpose of ajoint reception process by means of the reception nodes acting ascooperating nodes 3, 4. The analyzing unit is described in more detailin FIG. 7. The scheduling unit 8 is configured to perform a schedulingof the radio interface of the uplink transmissions from user equipmentunits UE1 during the joint reception process, which scheduling is basedon the backhaul capacity that is obtained by the analyzing unit 7. Thescheduling unit will be further described in FIG. 8.

FIG. 7 illustrates the analyzing unit 7 in more detail. The analyzingunit 7 comprises a radio quality obtainer 71 configured for obtaining anindication of communication quality between user equipment units UE1,UE2 and other reception nodes 3, 4 of the cellular radio communicationsystem 1. The radio quality obtainer 71 is adapted to obtain the radiocommunication quality in at least one of a number of different ways,which ways includes retrieving radio communication quality indicationsalready stored in the memory of the controller 12, request and receivethe indications of the radio communication quality from the userequipment units UE1, UE2, and request and receive the indications ofradio communication quality from the other reception nodes 3, 4 that arecandidates for being cooperating nodes 3 during a joint reception. Theradio quality obtainer 71 is preferably adapted to group the userequipment units UE1, UE2 into sets S1, S2 of user equipment units UE1,UE2, for example in accordance with equation 1 or equation 2, whereinuser equipment units UE1 having a certain radio communication qualitysuitable for reception by a cooperating node 3 is sorted in to a set S1.The set S1 is subsequently used when the radio resources are allocatedfor joint reception.

The analyzing unit 7 also comprises a radio resource analyzer 72 thatare configured for analyzing the available radio resources A so thatspecific radio resource elements B1, B2 can be subsequently selected fora joint reception process.

The analyzing unit 7 comprises a backhaul capacity obtainer 73. Theradio resource analyzer 72 is adapted to provide alternatives forallocating the radio resource elements B1, B2 on the backhaul capacityobtained by the backhaul in capacity obtainer 73. The radio resourceanalyzer 72 is adapted to determine a time period T of the availableradio resource A, A2 based on a maximum allowed latency for performingjoint detection in the cellular radio communication system 1. Further,the radio resource analyzer provides alternatives for a subsequentselecting, performed by the scheduling unit 8, which alternativesincludes radio resource element B1, B2, each being determined on thebasis of the available backhaul capacity, so as not to cause acongestion in the backhaul, neither in the cooperating node 3 nor in thebackhaul link 5. The radio resource elements are of a type from a groupof radio resource elements comprising a sub-frame element B1 consistingof at least one-sub frame of the whole frequency band being allocated toa user equipment unit UE1 during a sub-frame, and a sub-frequencyelement B2 consisting of a sub-band in a sub-frame A2 of the timeperiod, wherein the remaining part of sub-frame A2 is selected forsingle-node reception of transmissions from the same user equipment unitUE1.

The backhaul capacity obtainer 73 is configured to obtain a backhaulcapacity of selected, as selected by the scheduling unit 8, potentialcooperating nodes 3.

Especially, the backhaul capacity obtainer 73 is adapted to determine acomputing capacity of the cooperating node 3.

The backhaul capacity obtainer 73 is adapted to obtain a backhaulcapacity of each cooperating node 3, and the backhaul capacity comprisesan indication of latency, an indication of available bandwidth forsending the joint reception data on a link 5 of the backhaul and anindication of computing capacity of the cooperating node 3. The backhaulcapacity obtainer 73 is configured to employ the backhaul communicationinterface 13 for communicating with each cooperating node 3, especiallyfor the purpose of requesting and receiving an indication of thebackhaul capacity.

The analyzing unit 7 also comprises a data refinement determiner 74,which is configured to determine a level of refinement for the jointreception data that should be obtained by each cooperating node 3.Especially, the refinement determiner 74 is configured to determine alevel of refinement based on the computing capacity of the cooperatingnode 3, and/or load of the cooperating node 3. The refinement determiner74 is adapted to determine a higher level of refinement on the basis ofthe currently available bandwidth for transmissions from the cooperatingnode 3 in the respective backhaul link 5 being lower than the bandwidthof the uplink traffic from user equipment units UE1 belonging to set S1,for which set S1 of user equipment units UE1 a joint reception is atleast possible. In this way the serving node is adapted to match a levelof refinement with backhaul bandwidth and enable an optimizedutilization of the resources for performing a joint reception.

FIG. 8 illustrate the scheduling unit 8 of the serving node 2 in moredetail. The scheduling unit 8 comprises a user equipment selector 81configured to select 101 user equipment units UE1 for joint reception.The user equipment selector 81 is adapted to select the user equipmentunit UE1 from the set of user equipment units S1 that have been providedby the radio quality obtainer 71. The user equipment selector 81 isadapted to select a plurality of user equipment units UE1 for jointreception, which user equipment units UE1 subsequently are allocatedradio resource elements B1, B2 for joint reception in the radiointerface.

Since, the user equipment selector 81 selects the user equipment unitsfrom S1, the selection is based on the radio communication qualitybetween the user equipment units UE1 and the neighboring receptionnodes, especially selected cooperating nodes 3.

The scheduling unit 8 comprises a cooperating node selector 82configured to select cooperating nodes 3 for the joint reception. Thecooperating node selector 82 is adapted to select the cooperating nodes3 based on the obtained radio communication quality, as provided by theradio quality obtainer 71.

The scheduling unit 8 comprises a radio element selector 83 configuredto select radio resource elements B1, B2 for the joint reception. Eachradio resource element B1, B2 consists of at least one part of the radioresources A available for uplink transmissions. The available radioresource A are defined by a time period T comprising at least onesub-frame, or TTI (transmission time instance), preferably a pluralityof sub-frames, wherein each sub-frame defines a minimum time for onetransmission, and a frequency band comprising a plurality of sub-bandsprovided for scheduling in the cellular radio communication network 1.

The radio element selector 83 is adapted to select radio resourceelements B1, B2 based on a determined backhaul capacity as provided bythe backhaul capacity obtainer 73.

The radio element selector 83 being adapted to select radio resourceelements B1, B2 from a group of resource element types comprisingsub-frame elements B1 and sub-band elements B2. The sub-frame elementsB1 consisting of at least one-sub frame of a frequency band intended foruse for the total uplink transmissions from one user equipment unit UE1during one TTI. The sub-frequency elements B2 consisting of one sub-bandin one sub-frame TTI of the time period, wherein the sub-band elementsB2 is a part of a sub-frame intended for use by one user equipment unitUE1. The other part C2 of the sub-frame A2 is intended for single-nodereception of the transmissions from the same user equipment unit UE1.

The radio element selector 83 is, in an embodiment, adapted to selectradio resource elements B1, B2 based on a quality of service provided tothe user equipment unit UE1 in question. The radio element selector 83may in such an embodiment be adapted to select the type of the radioresource elements B1, B2 based on the quality of service level of theselected user equipment UE1.

The scheduling unit further comprises a first link adaptation selector84 configured to select link adaptation from a respective first andthird set of link adaptations, which first set of link adaptations isprovided for the allocation of sub-frame elements B1 for jointreception, and which third set of link adaptations is provided for theallocation of sub-band elements B2, C2, of which one of the sub-bandelements are used for joint receptions, and the other for single-nodereception.

The scheduling unit 8 further comprises a node reception scheduler 87configured for scheduling single-node reception of uplink transmissionsfrom the user equipment units UE1, UE2. The node reception scheduler 87comprises a second link adaptation selector 89 configured to select alink adaptation for resource elements A selected for single-nodereception only.

The first 84 and the second 89 link adaptation selectors are adapted toselect link adaptations from respective first, second and third set oflink adaptations, which first, second and third set are mutuallydifferent. Thus, the selecting of a link adaptation performed by theserving node 2 includes choosing a link adaptation for joint receptionthat is different from the link adaptation selected for single-nodereception. In this way an expected improvement of the reception providedduring the joint reception is used to provide a higher data rate in theradio interface during the joint reception. Also, the selecting of linkadaptation includes selecting a link adaptation for combined or mixedtransmissions, corresponding to a sub-frame A2 with sub-bands B2 and C2,that provides a data rate higher than the data rate for single-nodereception and lower than the data rate used for a pure joint reception.

The scheduling unit 8 further comprises a joint reception requester 85configured to order joint reception data by means of the backhaulcommunication interface 13. The joint reception requester 85 is adaptedto order joint reception data from the selected cooperating nodes, asselected by the cooperating node selector 82, by creating andtransmitting order messages to the cooperating nodes 3, which orderingmessages identifies the selected radio resource elements. The jointreception requester 85 is adapted to indicate the determined level ofrefinement, as provided by the refinement determiner 74, in the orderingmessages. The joint reception requester 85 is also adapted to includinga prioritization indication in the order message that is based on thequality of service (Q o S) of the user equipment unit UE1 in thecellular radio communication system 1. The joint reception requester 85is also adapted to include a prioritization indication in the ordermessage that is based on the type of radio resource elements used forthe joint reception. In alternative embodiments, such indications ofprioritization may be sent by the serving node 2 to the cooperatingnodes 3 separately and the joint reception requester 85 is adapted tosend prioritization requests in other messages than the joint receptionorder. The prioritization indication can be used both for schedulingpurposes and for prioritization between different messages that make useof backhaul capacity.

Prioritizations of uplink transmissions of a user equipment unit UE1 mayalternatively be made independently from the quality of service level,the joint reception requester 85 is in such a case adapted to include anindication of priority based on other grounds, such as a request forprioritization from a user equipment unit UE1.

The scheduling unit 8 further comprises a user equipment allocator 86that is configured to allocate the selected user equipment units UE1 foruplink transmission. The user equipment allocator 86 is configured totransmit allocating messages to allocated user equipment units UE1,which allocating messages identifies the selected radio resourceelements B1, A2 (i.e. B2+C2), and indicates the selected linkadaptation.

The user equipment allocator 86 is further adapted to select type ofradio resource element, B1 or A2 (B2+C2), based on a quality of servicelevel the selected user equipment UE1 is entitled to in the cellularradio communication network 1.

When a plurality of user equipment units UE1 have been selected forjoint reception, an allocating message is sent to each of the userequipment units UE1, each including an indication of radio resourceelement B1, A2 including B2, and link adaptation. Based on the qualityof service of each of the user equipment units UE1, the allocatingmessage includes indications of different types of radio resourceelement when the quality of service level differs for the user equipmentunits UE1. Thus a user equipment unit UE1 having a higher quality ofservice level may be allocated a prioritized radio resource element B2,whereas a user equipment unit UE1 having a lower quality of servicelevel is allocated a radio resource element B1 that is not prioritized,i.e. having a lower prioritization than the prioritized radio resourceelement B2.

The node reception scheduler 87 also includes a user equipment allocator88. This second user equipment allocator 88 is configured for allocatinguser equipment units UE1, UE2 for single-node reception only, during aspecific time sub-frame TTI.

The second user equipment allocator 88 is configured to allocate userequipment units UE1, UE2 for single-node reception by the serving node2. The second user equipment allocator 88 is adapted to allocate theuser equipment units UE1, UE2 to parts, especially sub-frames andsub-bands of sub-frames, of the radio resources A that is not selectedfor joint reception. The second user equipment allocator 88 is adaptedto select user equipment units UE1, UE2 only from set S2 as provided bythe radio quality obtainer 71. Alternatively, the second user equipmentallocator 88 is adapted to select user equipment units UE1, UE2 thatbelong to S1 and that belong to S2.

FIG. 9 illustrates the joint reception unit 9 of the serving node 2. Thejoint reception unit 9 comprises an uplink receiver 91 configured toreceive uplink transmissions from the user equipment units UE1 by meansof the radio communication interface 11. Especially, the uplink receiveris configured for receiving radio resource elements B1, B2 selected forjoint reception, directly from the user equipment units UE1.

The joint reception unit 9 also comprises a backhaul receiver 92configured to receive data by means of the backhaul communicationinterface 13. Especially, the backhaul receiver 92 is configured toreceive data for joint reception from a cooperating node 3, as obtainedfrom radio resource elements B1, B2 by cooperating node 3.

The joint reception unit 9 also comprises a joint receiver 93 configuredto perform a joint reception of the directly received uplinktransmissions and the obtained data of the uplink transmissions.Especially, the joint receiver is configured to obtain the directlyreceived uplink transmissions to the same level of refinement asreceived from the cooperating node 3.

FIG. 10 illustrates a network node that has been configured toparticipate in a joint reception process as a cooperating node 3. Thecooperating node 3 comprises a radio communication interface 20,especially for receiving uplink transmissions from user equipment unitsUE1 during a process of joint reception. The cooperating node 3comprises a backhaul communication interface 21, especially fortransmitting data, obtained from received uplink transmissions, to aserving node 2 when participating in a joint reception. The cooperatingnode 3 comprises a controller 22, especially configured to obtain datafor the joint reception, which data is obtained from uplinktransmissions of the user equipment units UE1 that are the subject ofthe joint reception. The controller 22 is illustrated as comprising aprocessor or controller 22 and a memory storing computer program codereferred to as an analyzing unit 30 and a joint reception cooperatingunit 40. The analyzing unit 30 can be seen as a computer program, whichwhen executed by the controller 22 makes the network node perform ananalysis of its radio communication quality (a program function 32) andbackhaul capacity (a program function 31). The joint receptioncooperating unit 40 can be seen as a computer program, which whenexecuted by the controller 22 makes the network node perform the methodsteps of a joint reception process (program functions 40-48), especiallyperforming the communication with the user equipment units UE1 by meansof the radio communication interface 20, and the communication with theserving node 2 by means of the backhaul communication interface.

Thus, the network node (3) is adapted for participating in a jointreception process, wherein uplink transmissions of a user equipment UE1,UE2 is received by the network node (3) acting as a cooperating node 3and also by a serving node 2, and wherein the cooperating node 3 isprovided to obtain data for from the received uplink transmissions andforward the obtained data to the serving node 2. The cooperating node 3is adapted for performing the method of FIG. 3 and FIG. 10 illustratesan embodiment of such a network node 3.

The analyzing unit 30 comprises a capacity determiner 31 and a radioquality determiner 32. The capacity determiner 31 is configured todetermine the currently available computing capacity of the cooperatingnode 3 for performing a process of obtaining data from the receiveduplink transmissions from the user equipment units UE1. The radioquality determiner 32 is configured to provide an indication of theradio communication quality of the radio interface between the userequipment units UE1 and the cooperating node 3, so that the possibilityof receiving the uplink transmissions from the user equipment unit UE1is established.

The illustrated controller 22 comprises a capacity messenger 47 that isconfigured to receive a backhaul capacity request from a serving node 2by means of the backhaul communication interface 21. The capacitymessenger 47 is configured to reply to the request by transmitting anindication of backhaul capacity to the serving node 2.

The controller 22 comprises a quality messenger 48 configured forreceiving a radio quality request from the serving node 2 and reply byan indication of the radio communication quality with the user equipmentunit UE1, which radio quality is determined by the radio qualitydeterminer 32. The radio quality determiner 32 is adapted determine theradio quality for example by receiving and measuring the strength oftransmissions from the user equipment unit UE1.

The capacity determiner 31 is configured to determine a capacity forreceiving transmissions, obtaining data and forwarding the obtained datato the serving node 2.

In a more detailed described embodiment, the capacity determiner 31 isadapted to determine a backhaul capacity that comprises an indication oflatency. The latency includes the latency, or delay, for receivinguplink transmissions from a user equipment unit, obtaining data from thereceived uplink, and forwarding the data including latency of thetransmission link between cooperating node and the serving node. Thecapacity determiner 31 is adapted to determine the available bandwidthof the backhaul link 5 that is currently available for sending theobtained data to the serving node 2. The capacity determiner 31 isadapted to determine, or obtain, its currently available computingcapacity. The capacity determiner 31 is adapted to determine thecommunication load it experiences at the present time.

The joint reception cooperating unit 40 of the cooperating node 3comprises an order obtainer 41 configured to receive orders for jointreception of radio resource elements B1, B2 from the serving node 2, bymeans of the backhaul communication interface 21. The order obtainer 41is adapted for receiving orders comprising an indication of a level ofrefinement of each resource element B1, B2. The order obtainer 41 isadapted for receiving orders comprising an indication of prioritizationof traffic from a specific user equipment unit UE1, and/or of specificresource elements B1, B2, and/or a specific type, or types, of radioresource elements B1, B2.

The joint reception cooperating unit 40 comprises an uplinktransmissions obtainer 42 configured to receive the radio resourceelements B1, B2 from user equipment units UE1 by means of the radiocommunication interface. The cooperating node 3 further comprises a dataobtainer 43 configured to obtain data from received radio resourceelements B1, B2, especially obtain demodulated data, de-spread data anddecoded data. The data obtainer 43 is adapted to obtain data from eachreceived radio resource element B1, B2 in accordance with the receivedjoint reception orders. The data obtainer 43 comprises a data refiner 44configured to refine obtained data in accordance with indications of alevel of refinement of the received radio resource elements B1, B2 whenthe received orders for joint reception comprises such an indication ofrefinement level. Thus, the data refiner 44 is adapted to provide thedata at the indicated level of refinement.

The levels of refinement that the data refiner 44 is adapted to providecomprises: time domain data; frequency domain (FFT) data symbols for theentire system bandwidth; user extracted frequency domain data symbols;equalized I/Q symbols; soft-bits and hard-bits.

The joint reception cooperating unit 40, of the cooperating node 3,comprises an element prioritizing unit 45 configured to prioritize theradio resource elements B1, B2 based on the user equipment unit UE1transmitting the radio resource element and/or the joint reception orderand/or the type of radio resource element B1, B2. The elementprioritizer 45 is configured to apply a prioritization so that theforwarding of data obtained from the prioritized radio resource elementB1, B2 is prioritized in relation to the data obtained from other radioresource elements B1, B2.

The joint reception cooperating unit 40 comprises a data messenger 46for forwarding the obtained data to the serving node 2 by means of thebackhaul link 5 using the communication interface 21. The data messenger46 is adapted to forward the obtained data in accordance with theprioritization, for example the prioritization indication received fromthe serving node 2, and obtained by the element prioritizer 45.

The invention has mainly been described above with reference to a fewembodiments. However, as is readily appreciated by a person skilled inthe art, other embodiments than the ones disclosed above are equallypossible within the scope of the invention, as defined by the appendedpatent claims.

The invention claimed is:
 1. A method in a cellular radio communicationnetwork, including scheduling traffic for joint reception, the methodbeing performed by a serving node and comprising: transmitting a firstradio quality request to at least one user equipment unit (UE1);transmitting a second radio quality request to at least one cooperatingnode; receiving a first radio quality message from the at least one userequipment unit (UE1) in response to the first radio quality request;receiving a second radio quality message from the at least onecooperating node in response to the second radio quality request;selecting the at least one user equipment unit (UE1) based at least onthe first radio quality message; selecting the at least one cooperatingnode based at least on the second radio quality message; selecting atleast one radio resource element, each radio resource element comprisingat least one part of the radio resources available for uplinktransmissions, the available radio resource being defined by a timeperiod (T) comprising at least one sub-frame defining a minimum time forone transmission (TTI), and a frequency band comprising a plurality ofsub-bands provided for scheduling in the cellular radio communicationnetwork; obtaining a backhaul capacity of each cooperating node; theselection of the at least one radio resource element being based on atleast one of the determined backhaul capacities; ordering jointreception data from each selected cooperating node by transmitting atleast one ordering message to each selected cooperating node, wherein atleast one ordering message identifies each selected radio resourceelement and allocating the selected at least one user equipment unit(UE1) for uplink transmission including transmitting at least oneallocating message to each allocated user equipment unit (UE1), whereinat least one allocating message identifies each selected radio resourceelement.
 2. The method according to claim 1, each selected radioresource element being of a type selected from a group of resourceelements comprising: a sub-frame element comprising at least one-subframe of the whole frequency band selected for transmissions from oneuser equipment unit (UE1); and a sub-frequency element comprising onesub-band of a frequency band also including a sub-band selected forsingle-node reception for transmissions from one user equipment unit(UE1).
 3. The method according to claim 2, wherein the selectingincludes selecting a plurality of user equipment units (UE1) for jointreception, and the allocating includes allocating each of the selecteduser equipment units (UE1) on respective selected radio resourceelements.
 4. The method according to claim 1, wherein the backhaulcapacity comprises one or more of an indication of latency, anindication of available bandwidth for sending the joint reception dataon a link of the backhaul, and an indication of computing capacity ofthe cooperating node.
 5. The method according to claim 1, wherein theorder message comprises indicating a level of refinement of eachresource element and one or more of an indication of priority fortransmissions in a specific resource element and transmissions from aspecific user equipment unit (UE1).
 6. The method according to claim 5,further comprising determining a level of refinement on the basis of thebackhaul capacity, wherein the backhaul capacity includes an indicationof computing capacity of the cooperating node.
 7. The method accordingto claim 1, further comprising receiving uplink transmission on eachselected radio resource element directly; receiving from eachcooperating node the data obtained from each selected radio resourceelement; and performing a joint reception of the directly receiveduplink transmission and the data from each cooperating node.
 8. Themethod according to claim 1, further comprising obtaining an indicationof communication quality between a user equipment unit (UE1, UE2) and atleast one other node for determining the possibility of performing ajoint reception, wherein the selecting of a user equipment unit (UE1)for joint reception is based on the obtained indication of communicationquality, and the selecting of at least one cooperating node is based onthe obtained indication of communication quality.
 9. The methodaccording to claim 1, further comprising determining a time period (T)of the available radio resource based on a maximum allowed latency forperforming joint detection.
 10. A node in a cellular radio communicationnetwork configured to act as a serving node when performing a jointreception, the node being adapted for scheduling traffic for jointreception, the node comprising: a user equipment selector configured toselect user equipment units (UE1) for joint reception; a cooperatingnode selector configured to select cooperating nodes for the jointreception; a radio element selector configured to select radio resourceelements for the joint reception, wherein each radio resource elementconsists of at least one part of the radio resources available foruplink transmissions, the available radio resource being defined by atime period (T) comprising at least one sub-frame defining a minimumtime for one transmission (TTI), and a frequency band comprising aplurality of sub-bands provided for scheduling in the cellular radiocommunication network; a joint reception requester configured to orderjoint reception data from selected cooperating nodes by transmittingordering messages to the selected cooperating nodes, which orderingmessages identifies the selected radio resource elements; a userequipment allocator being configured to allocate selected user equipmentunits (UE1) for uplink transmission including being configured totransmit allocating messages to allocated user equipment units (UE1),which allocating messages identifies the selected radio resourceelements; and a backhaul capacity obtainer configured to obtain abackhaul capacity of selected cooperating nodes, the radio elementselector being adapted to select radio resource elements based on adetermined backhaul capacity.
 11. The node according to claim 10, theradio element selector being adapted to select radio resource elementsfrom a group of resource element types comprising: a sub-frame elementcomprising at least one-sub frame selected for transmissions from oneuser equipment unit (UE1); and a sub-frequency element comprising onesub-band of a frequency band also including a sub-band selected forsingle-node reception for transmissions from one user equipment unit(UE1).
 12. The node according to claim 10, the backhaul capacityobtainer being adapted to determine a computing capacity of thecooperating node, the node further comprising a refinement determinerconfigured to determine a level of refinement based on the computingcapacity of the cooperating node, and the joint reception requesterbeing adapted to indicate the determined level of refinement in theordering messages.
 13. A method in a cellular radio communicationnetwork, including participating in joint reception, wherein an uplinktransmission of a user equipment (UE1, UE2) is received by a pluralityof reception nodes, one of the reception nodes being a serving node, atleast one of the reception nodes being a cooperating node, eachcooperating node being provided to obtain data for joint reception fromthe received uplink transmission and forward the obtained data to theserving node, the method being performed by a cooperating node andcomprising: receiving an order for joint reception of at least two radioresource elements from the serving node; receiving the at least tworadio resource elements; transmitting an indication of backhaul capacityto the serving node, which backhaul capacity comprises one or more of anindication of latency, and an indication of available bandwidth forsending the obtained data on to the serving node, and an indication ofcomputing capacity of the cooperating node, wherein the backhaulcapacity includes an indication of computing capacity of the cooperatingnode; obtaining data from each received radio resource element;forwarding the obtained data to the serving node; and prioritizing atleast one radio resource element of the at least two radio resourceelements before forwarding the obtained data, the data obtained from theprioritized radio resource element being forwarded before the dataobtained from the other radio resource element.
 14. The method accordingto claim 13, wherein the prioritization is based on one or more of thetype of the radio resource elements and/or an identity of the userequipment unit (UE1) in question, and an indication in the jointreception order that indicates priority to a specific resource element.15. The method according to claim 13, further comprising determining acapacity for receiving transmissions, obtaining data and forwarding theobtained data to the serving node.
 16. The method according to claim 13,further comprising determining an indication of communication qualitywith a user equipment (UE1, UE2) and transmitting the communicationquality indication to the serving node.
 17. The method according toclaim 13, wherein the received order comprises an indication of a levelof refinement of each resource element, and obtaining data beingperformed to the indicated level of refinement.
 18. A node configured toact as a cooperating node when performing a joint reception in acellular radio communication network, the node being adapted forobtaining data for joint reception from uplink transmission and forwardthe obtained data to a serving node, the node comprising: an orderobtainer configured to receive orders for joint reception of radioresource elements from the serving node; an uplink transmissionsobtainer configured to receive the radio resource elements from userequipment units (UE1); a capacity messenger configured to transmit anindication of backhaul capacity to the serving node; comprising acapacity determiner configured to determine a capacity for receivingtransmissions, obtaining data and forwarding the obtained data to theserving node, and the capacity messenger being adapted to indicatebackhaul capacity based on the determined capacity; a data obtainerconfigured to obtain data from received radio resource elements; a datamessenger configured to forward the obtained data to the serving nodeand an element prioritizing unit configured to employ a prioritizationof the radio resource elements, the data obtained from the prioritizedradio resource element being forwarded by the data messenger before thedata obtained from the other radio resource element.
 19. The nodeaccording to claim 18, further comprising a data refiner configured torefine obtained data in accordance with indications of a level ofrefinement for the resource elements when received orders for jointreception comprises such an indication.
 20. The node according to claim18, wherein the element prioritizing unit is adapted to make theprioritization on the basis of one or more of the type of the radioresource elements, an identity of the user equipment unit (UE1) inquestion, and an indication in the joint reception order that indicatespriority to a specific resource element.